Flam on Bayes’s Theorem

September 30, 2014 • 11:07 am

Official Website Science Journalist™ Faye Flam, who gave us a nice guest post a while back about how to talk to reporters, has her first article up in today’s Science Times at the New York Times, “The odds, continually updated.” It’s about Bayes’s Theorem, a way to calculate probabilities if you have some prior information about related probabilities, and I have a feeling that a lot of our science readers know about it. But even if you do, you should check out Faye’s piece, as it has some nifty ways the theorem has been used, like narrowing the search for a lost fisherman. (She makes the case, and it’s pretty strong, that the theorem actually saved that fisherman’s life.)

It’s a nice summary, covering the origin of the theorem, what it means, how it’s used and how probabilities calculated from that theorem differ from conventionally calculated probabilities. It’s a lot of information packed into a readable and concise format. Here’s one bit about the Monty Hall problem. (Try telling one of your friends about it and then tell them that they should always switch doors. Odds are they won’t believe you!):

A famously counterintuitive puzzle that lends itself to a Bayesian approach is the Monty Hall problem, in which Mr. Hall, longtime host of the game show “Let’s Make a Deal,” hides a car behind one of three doors and a goat behind each of the other two. The contestant picks Door No. 1, but before opening it, Mr. Hall opens Door No. 2 to reveal a goat. Should the contestant stick with No. 1 or switch to No. 3, or does it matter?

A Bayesian calculation would start with one-third odds that any given door hides the car, then update that knowledge with the new data: Door No. 2 had a goat. The odds that the contestant guessed right — that the car is behind No. 1 — remain one in three. Thus, the odds that she guessed wrong are two in three. And if she guessed wrong, the car must be behind Door No. 3. So she should indeed switch.

Jasen Rosenhouse wrote a whole book about the Monty Hall problem, which you can find at this link.

Anyway, Faye manages to write the whole article without once showing the theorem itself, but nevertheless captures its essence. It’s good popular science writing. And here’s the theorem:

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Addendum: Faye also has a new piece in Forbes which will interest many of us: it’s about why plants make caffeine. The piece is called,”Though it may taste divine, coffee DNA tells a Darwinian tale.” I won’t give you the punchline, but here’s a teaser:

But caffeine appears to be extra beneficial to plants since it evolved through different genetic mutations in coffee, chocolate and tea – a phenomenon called convergent evolution. We know why we like coffee, but what’s in it for these different plants?

Making a virtue of necessity: doubt as “a crucial part of faith”

September 30, 2014 • 7:35 am

On September 18 I discussed the confession of Justin Welby, the Archbishop of Canterbury, that he had experienced some heavy doubts about God’s existence, based on God’s distressing lack of appearance on the planet. Surprisingly, though, Welby had no doubts about Jesus. I found that quite astonishing, for Jesus has meaning to Welby only as the son of God (as well as a third of the Godhead, given that Anglicans accept the Trinity). How can you doubt God and be certain about the divinity of Jesus?

At any rate, Julia Baird (an Australian opinion writer for the New York Times who also has a Ph.D. in history) has taken to her keyboard to defend Welby in a Sept. 25 Times op-ed,, “Doubt as a sign of faith.”  Her thesis is, in her words, this: “Doubt is a crucial part of faith.”

But her piece does not start off well:

Certainty is so often overrated.

This is especially the case when it comes to faith, or other imponderables.

Overrated? Wouldn’t you want to be certain that your faith was right? After all, you’re staking a lot of your life, and all of your afterlife, on what you believe. And certainty in other matters, so long as it’s supported by evidence, is what you want. (I think she’s talking about real empirical certainty, not simply one’s assertion that one is right.)

To defend her thesis, Baird first lists some religious people who have had religious doubts, including Welby himself , Mother Teresa (her diary entries on this are now well known), C. L. Lewis, Flannery O’Conner, Benjamin Franklin, and even Jesus himself, who, says Baird, cried out on the cross, “My God, why have you forsaken me?” Well, that might not be Jesus’s doubt about God’s existence, but anguish about why God didn’t save him.

Indeed, according to scripture Jesus did say that, but in only two of the four Gospels, Matthew and Mark. Here are his final words in all four gospels:

  • Luke 23:34: Father, forgive them, for they do not know what they do.
  • Luke 23:43: Truly, I say to you, today you will be with me in paradise.
  • John 19:26–27: Woman, behold your son.Son Behold your mother.
  • Matthew 27:46 & Mark 15:34 My God, My God, why have you forsaken me?
  • John 19:28: I thirst.
  • John 19:29-30: It is finished.
  • Luke 23:46: Father, into your hands I commit my spirit.

If Baird quoted Luke or John, we wouldn’t see that doubt, so she’s cherry-picking. Did Luke and John simply leave out those crucial words of doubt, or did someone make them up? (Baird appears to believe they are real, for she implies, as we’ll see below, that she’s a Baptist.)

But never mind. Her view that doubt is inherent in faith, is largely (but not completely) correct. How can it not be for many? If you’re committed to believing a bunch of superstition lacking evidence, and yet you’re a thinking person who bases the rest of your life on things for which you’d like evidence, then sometimes you must wonder if all this stuff is real.  That’s all well and good, but, given the nature of faith, how does one resolve those doubts? This is the question Baird avoids:

Just as courage is persisting in the face of fear, so faith is persisting in the presence of doubt. Faith becomes then a commitment, a practice and a pact that is usually sustained by belief. But doubt is not just a roiling, or a vulnerability; it can also be a strength. Doubt acknowledges our own limitations and confirms — or challenges — fundamental beliefs, and is not a detractor of belief but a crucial part of it.

This is truly making a virtue of necessity.  For there is no good way for a believer to actually resolve those doubts, for there is no evidence to appeal to. How can Welby call on evidence to convince himself that God really exists? After all, it’s that lack of evidence that raised his doubts in the first place! At least Baird admits that faith is “persisting in the presence of doubt,” that is, pretending that something exists when you’re not sure it does.

No, there are only two ways to quell those doubts. First, just decide to quietly shelve them and convince yourself that you were right all along, or conjure up some “evidence,” like a frozen waterfall or a beautiful evensong, to get you back on track.  But that is just confirmation bias. Or, you can do what Baird’s pastor does, and just say that maybe it doesn’t matter if what you believe is true, so long as it produces good things:

My local pastor, Tim Giovanelli, a Baptist whose ocean-swimming prowess has lassoed scores of surfers and swimmers into his church, puts it simply: “For Welby, myself and many others, it is not that we have certainty but have seen the plausibility of faith and positive impact it can make. In a broken world, that can be enough.”

But where does the “plausibility” come from? Doesn’t Giovanelli really mean “logical possibility”? It is the mistaking of the logical possibility (and emotional appeal) of a God for the plausibility of a God (something that Alvin Plantinga does continually, and on purpose), that mistakenly leads the doubters back to faith.

Yes, religious doubt is natural, and inevitable in rational people, but the whole goal of religion is to quash it. Granted, some, like Welby, will admit it (though I suspect that people like Al Mohler, Ken Ham, and William Lane Craig don’t have such doubts), but in the end they always decide that they were right all along—on no evidence—and plow ahead as before, like a ship going around an iceberg. I doubt that Welby’s newfound doubts will affect his sermons or public pronouncements from now on: he will certainly act as if God and Jesus exist when he talks to his flock.

At the end, Baird compares the doubts of believers with those of rationalists, quoting the mathematician and philosopher Bertrand Russell:

If we don’t accept both the commonality and importance of doubt, we don’t allow for the possibility of mistakes or misjudgments. While certainty frequently calcifies into rigidity, intolerance and self-righteousness, doubt can deepen, clarify and explain. This is, of course, a subject far broader than belief in God. [JAC: Really?  How can religious doubt itself  “clarify and explain” without some way of resolving it?]

The philosopher Bertrand Russell put it best. The whole problem with the world, he wrote, is that “the stupid are cocksure while the intelligent are full of doubt.”

But there are two differences between the kind of doubt evinced by Baird and that mentioned by Russell.  First, when a scientist or empiricist doubts something, say string theory, they don’t go around proclaiming that it is true. They admit constantly that it is plausible but unsettled. Scientific “truth” only comes with substantial empirical verification. In contrast, the believers who have doubts, like Welby, ultimately go their merry way and forget that they had those doubts, saying that they’ve been resolved by further reflection. But reflection can’t resolve doubt unless you have a way of adjudicating the conflicting positions.

And that brings us to a crucial difference between religion and science. In science doubts are resolved by evidence. If you don’t have evidence that string theory is correct, you don’t tell yourself and others, “upon deeper reflection, I have clarified to myself that it is indeed right.” If you don’t have good evidence, you stop promoting your theory as the truth; instead, you persist in asserting that it’s undecided. But will be a cold day in July (in the northern hemisphere!) when Welby and Baird, who have even less evidence for God than physicists have for string theory, start doubting God’s existence publicly and frequently. Unless the doubts of the faithful are resolved by “deep reflection”—almost always the case—they become nonbelievers.

Baird’s article is a prime example of what I call The Great Sausage Machine of Theology: a mental appartus that converts scientific and empirical necessities—in this case a lack of evidence for one’s beliefs—into theological virtues.  And, like sausage-making, the working of the Theological Grinder are best kept hidden. By exposing them, Baird has revealed their intellectual vacuity.

Francis Crick hosts a groovy party

September 30, 2014 • 6:13 am

by Matthew Cobb

As regular readers will know, Jerry and I are finishing up our books at the same time. His is The Albatross, mine has a name and a topic ‘Life’s Greatest Secret: The Race to Crack the Genetic Code’. I hope to press ‘send’ to my publishers tomorrow morning. [JAC: Mine is hard on the heels of Matthews’]

One of the final things I’ve been doing is finding interesting photos that aren’t usually used in history books (will The Albatross have photos?).[JAC: No photos]. I came across this photo of Francis Crick, reclining in the foreground, at a party in his Cambridge house in the 1960s. They all look the worse for wear, under the influence of who knows what recreational chemicals. The leg in the very front of the picture is sporting a rather fancy pair of tights…

As you can see from the watermark, the photo is taken from Science Photo Library. The official caption is:

Crick hosting a flower party in the 1960s. This party was hosted by British biologist Francis Crick (1916-2004) and his wife Odile Crick (1920-2007). Crick is lying on the floor at lower centre, with his back to the camera. Francis and Odile had married in 1949, and this party was held at their house ‘The Golden Helix’ at 19 Portugal Place, Cambridge, UK. The dress code was ‘beads, bells, flowers’. It was in Cambridge that Crick and his co-workers had discovered the double helix structure of DNA in 1953. Crick, Watson and Wilkins shared the 1962 Nobel Prize for Physiology or Medicine.

 

Readers’ wildlife photos

September 30, 2014 • 5:02 am

Nature red in tooth and claw, from reader Peter Nothnagle:

Herewith attached, for your possible inclusion among the readers’  wildlife photos, a juvenile Cooper’s Hawk (Accipiter cooperii) dining on an unfortunate sparrow (Passer domesticus), observed by its sibling and an incredulous bunny (Sylvilagus floridanus).

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Reader Tony Eales has some photos from Oz:

I’ve just came back from a recent work trip to the outback and thought you might like to see a couple of the local residents.

I found a Shingleback or Stumpy Tail Skink (Tiliqua rugosa) walking across the road. They’re interesting for several aspects of their reproductive biology; there is a great deal of evidence that they form very long term monogamous pairs, they are viviparous with a placenta and because of the heavy armour the female organs like their lungs are pushed so far out of the way they can barely move or breath in the last part of pregnancy (their pregnancy lasts around 5 months).

Shingleback

I also saw a lot of emus (Dromaius novaehollandiae). There had been good rain for a few years and they were mostly groups of young adults foraging together. Their reproduction is interesting too with males looking after multiple eggs from multiple females then guarding and raising a group of chicks to young adulthood.

emu

There were also clouds of Budgies (Melopsittacus undulates) as well as many other parrots. I think they’re called pet parakeets in the US.

Budgie

From Stephen Barnard in Iowa, a bull and calf moose (Alces alces). He notes, “The bull was in rut and I was a little nervous about it.”

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Diana MacPherson

September 30, 2014 • 3:56 am

This is the first post I’ve ever titled with a reader’s name, but it came to me instantly when I saw this picture.

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If you don’t know what this means, you ain’t been around long enough. But I’m sure someone will explain in the comments.

Photo from Pet Stuff Web, in a series of ten cat confessions that are all worth seeing (especially the one involving “Grandmother’s ashes”).

Tuesday: Hili dialogue

September 30, 2014 • 2:41 am

When the dialogues are this enigmatic, I ask Malgorzata to explain them. Here’s what she said:

Hili’s stance indicates that she is seeing something, something tangible, something material. So she pronounced that she was seeing something. Andrzej asked what it was. And it turned out that Hili was peering into the future and could see the new times (new world order). She didn’t like what she saw and she shuddered out of dread.

Or it can just be that she sees winter coming… this is simpler explanation.

As always, we won’t know, for the ways of Cats are inscrutable.

Hili: I see.
A: What do you see.
Hili: New times.
A: And?
Hili: I shudder already.

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In Polish:
Hili: Widzę.
Ja: Co widzisz?
Hili: Nowe czasy.
Ja: I co?
Hili: Już mi zimno.

RIP Flippy

September 29, 2014 • 3:14 pm

I am deeply saddened to announce the death of one of our readers’ cats.  Flippy, the beloved master of biologist Sarah Crews (who has contributed readers’ wildlife photos to the daily feature), was euthanized last Wednesday after a long bout of illness of unknown cause.

Flippy was 12 or 13.

She was a beautiful female sealpoint snowshoe, and Sarah has memorialized her on her website Crews Control in a post called “Flippy’s Story.”  The post was actually written when Flippy was in bad shape but not yet dead, and it looked as though she would have to be “put to sleep”.  And she was, shortly thereafter.

My condolences to Sarah. Losing a long-time pet isn’t all that different from losing a human friend. In fact, it can be just as bad.

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